Legged mobile robot controller, legged mobile robot and legged mobile robot control method

ABSTRACT

A legged mobile robot, a legged mobile robot controller and a legged mobile robot control method are provided to perform a loading operation to load a gripped object in parallel on a target place having a height where a stretchable range of arm portions of the legged mobile robot is enhanced with no operator&#39;s handling. The legged mobile robot includes the arm portions having links for gripping an object, and leg portions having links for moving, and the arm and the leg portions are joined to a body thereof. The legged mobile robot controller includes a data acquisition unit, a whole-body cooperative motion control unit and a loading detection unit, and controls motions of the legged mobile robot based on posture/position data regarding a posture/position of each link of the legged mobile robot and on an external force data regarding an external force affecting the arm portions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No.2005-358353 filed on Dec. 12, 2005, the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a legged mobile robot using legportions, a legged mobile robot controller for controlling the leggedmobile robot, and a legged mobile robot controlling method.

2. Description of the Related Art

There have been known legged mobile robots walking or running(hereinafter referred to as “moving”) by legs. Such robots usually havea human-like figure with a head, arm portions, a body and leg portions,thereby encouraging natural communication with humans.

Robots, specifically industrial robots, usually assemble components,grip an object and transfer a product, or the like.

Those industrial robots are generally constituted merely of arm portionsfor assembling components or for grasping an object (often referred toas a “robot hand” or “robot arm”)

Such a “robot hand” as disclosed in JP2004-160594A is designed so as todetermine a grasp motion by calculating an approximate figure of anobject to be grasped, based on a touch sensor, an open angle sensor orthe like.

In addition, such a “robot grip controller” as disclosed inJP2004-167674A is designed to detect on an external force sensor a valueof an external force affecting a robot hand that grips an object, andincrease or decrease a grip force of the robot hand to grip the objectin accordance with changes of the external value, thereby receiving andhanding out the object.

If a legged mobile robot is provided with those well-known robot handsor a grip controller so as to grip an object and load the object on anappropriate place under an autonomous control with no operator'scontrol, the legged mobile robot cannot keep the object in parallel andtilt it, resulting in losing a balance in keeping the posture thereof.

In particular, there have been a disadvantage that, if the legged mobilerobot grips the object with the arms thereof and loads the grippedobject on the appropriate place (e.g. on a table with a predeterminedheight), a height of the appropriate place on which the object is loadedis limited within a stretchable range of the robot's arms, compared to aconventional robot arm.

The present invention has an object to provide a legged mobile robotcontroller, a legged mobile robot and the legged mobile robot controlmethod, which make it possible to load a gripped object on a targetplace having a height where a stretchable range of the arms is enhanced,while maintaining the posture of the legged mobile robot in accordancewith a predetermined posture with no operator's handling, therebysolving the above disadvantage.

SUMMARY OF THE INVENTION

In one aspect of the present invention, there is provided a leggedmobile robot controller for controlling a legged mobile robot comprisingarm portions for gripping an object, each arm potions having links; legportions for moving, each leg portion having links; a main body of thelegged mobile robot joined to the arm portions and the leg portions,based on posture/position data regarding a posture and a position ofeach link of the legged mobile robot and on an external force dataregarding an external force affecting the arm portion or portionsthereof.

The legged mobile robot controller includes a data acquire unit foracquiring the posture/position data and the external force data; awhole-body cooperative motion control unit for controlling motions ofthe leg portions in accordance with motions of the arm portions, basedon the posture/position data acquired by the data acquire unit, when thelegged mobile robot loads the gripped object with the arm portions on atarget place; and a loading detection unit for detecting that thegripped object with the arm portions has been loaded on the target placeby the motions controlled by the whole-body cooperative motion controlunit, based on the external force data acquired by the data acquireunit.

In this aspect, the whole-body cooperative motion control unit controlsin such a manner that, if the loading detection unit detects that thegripped object is not loaded on the target place when a position of thearm is put down or stretched, each link of the leg portions is bent atpart where each link is jointed to each other.

In another aspect of the present invention, there is provided a leggedmobile robot controller for controlling a legged mobile robot comprisingarm portions for gripping an object, each arm potion having links; legportions for moving, each leg portion having links; a main body of thelegged mobile robot joined to the arm portions and the leg portions,based on posture/position data regarding a posture and a position ofeach link of the legged mobile robot and on an external force dataregarding an external force affecting the arm portion or portionsthereof.

The legged mobile robot controller includes a data acquire unit foracquiring the posture/position data and the external force data; awhole-body cooperative motion control unit for controlling motions ofthe leg portions and the arm portions when the legged mobile robot Rloads the object gripped with the arm portions on a target place basedon the posture/position data acquired by the data acquire unit, themotions of the leg portions and the arm portions being controlled insuch a manner that: a polyhedron is formed by connecting, as apexesthereof, a movable point of each part or link of the arm portions andthe leg portions, and if the polyhedron sticks out at either of a firstpair or a second pair of the apexes thereof which are disposeddiagonally to each other, the polyhedron also sticks out at the otherpair of the apexes, so as to compensate the stick-out of the polyhedronat the apexes each other; and a loading detection unit for detectingthat the gripped object with the arm portions is loaded on the targetplace by the motions controlled by the whole-body cooperative motioncontrol unit, based on the external force data acquired on the dataacquire unit.

In this aspect, the apexes of the polyhedron at least includes positionsof gripper ends that are part of the arm portion; movable points of thelinks at which the arm portions and the main body are joined to eachother; movable points of the links at which the leg portions and themain body are joined to each other; and positions of heels or knees thatare part of the leg portions.

Furthermore in another aspect of the present invention, there areprovided legged mobile robot control methods for providing controls byusing the above legged mobile robot controllers, as well as a leggedmobile robot including the above legged mobile robot controllers.

Other features and advantages of the present invention will become moreapparent from the following detailed descriptions of the invention whentaken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of the outline of a legged mobilerobot.

FIG. 2 is a schematic perspective view showing a drive mechanism of thelegged mobile robot of FIG. 1.

FIG. 3 is a block diagram showing a configuration of the legged mobilerobot of FIG. 1.

FIG. 4 is a block diagram showing the legged mobile robot controller ofFIG. 3.

FIG. 5 is a flow chart explaining an overall operation of the leggedmobile robot.

FIG. 6 is a flow chart explaining a loading operation of variousoperations of the legged mobile robot.

FIGS. 7A to 7C are schematic diagrams showing each sequence of transfer,loading and return operations of the legged mobile robot.

FIGS. 8A to 8C are drawings for specifically explaining how tocompensate stick-out of a polyhedron formed by connecting movable pointsof each link of the legged mobile robot.

FIGS. 9A and 9B are drawing showing a difference between an uncontrolledcase and a controlled case by the legged mobile robot controller,regarding securing an operation zone.

FIGS. 10A to 10D are drawings showing differences between anuncontrolled case and a controlled case by the legged mobile robotcontroller, regarding a compliance control on arm portions and acompensation of wrist movable angle.

FIGS. 11A and 11B are drawings showing a difference between anuncontrolled case and a controlled case by the legged mobile robotcontroller, regarding a specific operation zone.

FIG. 12 is a plan view showing secured zones for the operation zone ofFIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Detailed descriptions will be given on an embodiment of the presentinvention, with reference to attached drawings.

The descriptions will be given first on outline of a legged mobilerobot, and drive mechanism and configuration of the legged mobile robot,next on a configuration of the legged mobile robot controller, and thenon an overall operation thereof from receiving an object to loading it.Thereafter, detailed descriptions will also be given on an operation ofloading an object, which is performed by the legged mobile robot.

Outline of Legged Mobile Robot

FIG. 1 is a schematic diagram of the outline of a legged mobile robot R.

As shown in FIG. 1, the legged mobile robot R is an autonomoustwo-legged mobile robot. The legged mobile robot R stands up withtwo-leg portions R1 (only one leg is shown in FIG. 1) and is providedwith an body R2, two arm portions R3 (only one arm portion is shown inFIG. 1) and a head R4 in such a manner that the robot R autonomouslymoves (walks or runs, etc.) as human does. The legged mobile robot R isprovided with a controller housing unit R5 for controlling operations onthe leg portions R1, the body R2, the arm portions R3 and the head R4 ona back thereof (back side of the body R2). Hereinafter, it is assumedthat a back and forth direction of the legged mobile robot R is an Xaxis, a lateral direction thereof is a Y axis and a vertical directionis a Z axis.

Drive Mechanism of Legged Mobile Robot

A description will be given on a drive mechanism of the legged mobilerobot R. FIG. 2 is a schematic perspective view showing a drivemechanism of the legged mobile robot R as shown in FIG. 1. Note thateach joint shown in FIG. 2 is depicted with an electric motor thatdrives each joint of the legged mobile robot R.

<Leg Portions R1>

As shown in FIG. 2, each leg portion R1 on the right and left sides isprovided with six joints 11R (L) to 16R (L) (hereinafter “R” denotes theright side and “L” denotes the left side, which are omittedoccasionally). The twelve joints on the right and left sides in totalare constituted of hip joints 11R and 11L on the hip (joint part betweenthe body R2 and the leg R1) for swirling the leg portions (about the Zaxis), hip joints 12R, 12L about a pitch axis (Y axis) of the hip, hipjoints 13R, 13L about a roll axis (X axis) of the hip, knee joints 14R,14L about a pitch axis (Y axis) on knees, ankle joints 15R, 15L about apitch axis (Y axis) of ankles, and ankle joints 16R, 16L about a rollaxis (X axis) of the ankles. Feet 17R, 17L are provided beneath the legportions R1.

Each leg portion R1 has the hip joints 11R(L), 12R(L), 13R(L), the kneejoint 14R(L) and the ankle joints 15R(L), 16R(L). The hip joints 11R(L)to 13R(L) and the knee joint 14R(L) are jointed through thigh links 51R,51L respectively. The knee joint 14R(L) and the ankle joints 15R(L),16R(L) are jointed through the leg links 52R, 52L respectively.

<Body R2>

As shown in FIG. 2, the body R2 is a main body part of the legged mobilerobot R and is jointed to the leg portions R1, the arm portions R3 andthe head R4. That is, the body R2 (body link 53) is jointed to the legportions R1 via the hip joints 11R(L) to 13R(L). The body R2 is alsojointed to the arm portions R3 via shoulder joints 31R(L) to 33R(L). Thebody R2 is jointed via neck joints 41, 42 (described later) to the heardR4, and has joint 21 for swirling the body (about the Z axis).

<Arm Portions R3>

As shown in FIG. 2, each arm portion R3 on the left and right sides isconstituted of seven joints 31R(L) to 37R(L). The fourteen joints on theright and left sides in total are constituted of shoulder joints 31R 31Labout a pitch axis (Y axis) of the shoulders (joint part between theshoulder R3 and the body R2), shoulder joints 32R, 32L about a roll axis(X axis) of the shoulders, shoulder joints 33R, 33L for swirling the armportions (about the Z axis), elbow joints 34R, 34L about a pitch axis (Yaxis) of elbows, arm joints 35R, 35L for swirling wrists (about the Zaxis), wrist joints 36R, 36L about a pitch axis (Y axis) of the wrists,and wrist joints 37R, 37L about a roll axis (X axis) of the wrists. Thearm portions R3 is provided with grippers (hands) 71R, 71L at each endthereof.

Specifically, each arm portion R3 on the right and left sides isconstituted of the shoulder joints 31R(L), 32R(L), 33R(L), the elbowjoints 34R(L), the arm joints 35R(L) and the wrist joints 36R(L),37R(L). The shoulder joints 31R(L) to 33R(L) and the elbow joint 34R(L)are jointed through a upper arm link 55R(L) respectively.

<Head R4>

As shown in FIG. 2, the head R4 is constituted of a neck joint 41 of theneck (joint part between the head R4 and the body R2) about a Y axis,and the neck joint 42 about a Z axis of the neck. The neck joint 41serves for defining a title angle of the heard R4. The neck joint 42serves for defining a pan angle of the head R4.

The above-mentioned drive mechanism provides the arm portions R1 on theright and left sides with twelve degree-of-freedoms in total, therebydriving the twelve joints 11R(L) to 16R(L) at an appropriate anglerespectively when the legged mobile robot R moves. Accordingly adesirable motion can be provided for the leg portions R1, so that thelegged mobile robot R can move as desired in the three dimensionalspace. The arm portions R3 on the right and left sides are provided withfourteen degree-of-freedoms in total, thereby driving the fourteenjoints 31R(L) to 37R(L) at an appropriate angle respectively when thelegged mobile robot R performs a desired operation, so that the leggedmobile robot R can operate as desired.

A conventional 6-axis force sensor 61R(L) is provided between the anklejoints 15R(L), 16R(L) and the foot 17R(L). The 6-axis force sensor61R(L) detects three direction components of a floor reaction force Fx,Fy, Fz that affect the legged mobile robot R from the floor, and threedirection components of a moment Mx, My, Mz.

A conventional 6-axis force sensor 62R(L) is provided between the wristjoints 36R(L), 37R(L) and the gripper 71R(L). The conventional 6-axisforce sensor 62R(L) detects three direction components of a floorreaction force Fx, Fy, Fz that affect the gripper 38 R(L) of the leggedmobile robot R, and three direction components of a moment Mx, My, Mz.

The body R2 is provided with a tilt sensor 63, which detects a tiltrelative to the gravity axis (Z axis) of the body R2 and an angularvelocity thereof.

The electric motor of each joint provides relative displacement betweenthe thigh link 51R(L) and the leg link 52R(L) or the like by usingreduction gears (not shown) to reduce and increase the motor rotationspeed. A joint angle detector (such as a rotary encoder) detects anangle at each joint.

The controller housing unit R5 stores an autonomous motion controller150 (described later, see FIG. 3), a gripper controller 160, a wirelesscommunication unit 170, a main controller 200 and a battery (not shown),etc. Data detected by each sensor 61 to 63 is transmitted to eachcontroller or control unit in the controller housing unit R5 and to thelegged mobile robot controller 1 (described later). Each electric motoris actuated by drive instruction signals transmitted from each controlunit.

Configuration of Legged Mobile Robot

FIG. 3 is a block diagram showing a configuration of the legged mobilerobot R of FIG. 1. As shown in FIG. 3, the legged mobile robot R isconstituted of cameras C, C, a speaker S, microphones MC, MC, an imageprocessor 100, an audio processor 110, an object detector 120, anautonomous motion controller 150, a gripper controller 160, a wirelesscommunication unit 170, a main controller 200, a storage device 300 andthe legged mobile robot controller 1, as well as the leg portions R1,the arm portions R3 and the head R4.

The legged mobile robot R is also provided with a gyro sensor SR1 and aGPS receiver SR2. The gyro sensor SR1 is used for detecting data ondirections (direction data) of the legged mobile robot R. The GPSreceiver SR2 is used for detecting data on positions (position data) ofthe legged mobile robot R. Data detected by the gyro sensor SR1 and theGPS receiver SR2 is outputted to the main controller 200, which is usedfor determining operations of the legged mobile robot R.

<Cameras>

The cameras C, C read images as digital data, and color CCD cameras maybe used for the cameras C, C, for example. The cameras C, C are disposedon the right and left sides in parallel, and images taken by the camerasC, C are outputted to the image processor 100. The cameras C, C, thespeaker S and microphones MC, MC are all installed in the head R4.

<Image Processor>

The image processor 100 is used for processing images taken by thecameras C, C, and recognizes obstacles and persons nearby based on theprocessed images, so as to grasp conditions surrounding the leggedmobile robot R. The image processor 100 is constituted of a stereoprocessing unit 101, a mobile object extraction unit 102 and a facerecognition unit 103.

The stereo processing unit 101 is used for performing pattern matchingbased on either of two images taken by the right and left cameras C, C,calculating parallax between each corresponding pixel in the right andleft images, so as to generate a parallax image and output the generatedparallax image and the original image to a mobile object extracting unit102. Note that the parallax mentioned herein represents distance fromthe legged mobile robot R to an object of which images are taken by thecameras C, C.

The mobile object extraction unit 102 is used for extracting a mobileobject in the image taken by the cameras C, C based on the dataoutputted from the stereo processing unit 101. An aim of extracting themobile object is to assume that the mobile object is a person andrecognize a face of the person.

For the purpose of extracting the mobile object, the mobile objectextraction unit 102 stores several (image) frames in the past, comparesprevious frames with a latest frame to perform pattern matching,calculates motion amount of each pixel, and generates a motion amountimage based on the calculated motion amount. From results of theparallax image and the calculated motion amount image, if it isdetermined that there are pixels with greater motion amount within apredetermined distance range, the mobile object extraction unit 102assumes that there is a person at the position of the pixels, extractsthe mobile object based on the parallax image only within thepredetermined distance range, and outputs the image of the mobile objectto the face recognition unit 103.

The mobile object extraction unit 102 also calculates a height of theextracted mobile object and outputs data on the height to the facerecognition unit 103. In other words, the mobile object extraction unit102 determines a position of a person (the mobile object) relative tothe legged mobile robot R, and his or her height as well.

The face recognition unit 103 extracts areas in skin color from theextract mobile object and recognize a face position based on a size,shape and the like of the extracted part. Similarly, a hand position isrecognized based on a size, shape and the like of the area in skincolor.

Data on the position of the recognized face is outputted to the maincontroller 200 and to the wireless communication unit 170, and thentransmitted to a station 2 (for performing wireless communicating withthe legged mobile robot R), as data for use when the legged mobile robotR moves and communicates with the recognized person.

<Speaker>

The speaker S outputs speech sounds based on speech sound data generatedby an audio synthesis unit 111 (described later)

<Microphones>

The microphones MC, MC collect sounds surrounding the legged mobilerobot R. The collected sounds are outputted to a speech recognition unit112 and a sound source location unit 113 (both described later).

<Audio Processor>

The audio processor 110 is constituted of an audio synthesis unit 111,the speech recognition unit 112 and the sound source location unit 113.

The audio synthesis unit 111 is used for generating speech sound datafrom character information, in accordance with instructions on speechbehavior that is determined by and outputted from the main controller200, and outputs the generated speech sound signals to the speaker S.When generating the speech sound data, a mapping scheme may be used toprovide a correlation between the character information and the speechsound data that are previously stored.

The speech recognition unit 112 is used for receiving speech sound datathrough the microphones MC, MC, generates character information from thespeech sound data by using the mapping data between the speech soundsand the character information that are previously stored, and outputsthe generated character information to the main controller 200.

The sound source location unit 113 determines a source sound location(distance and direction from the legged mobile robot R).

<Object Detector>

The object detector 120 detects whether or not there is an object to bedetected (not shown) carrying a detection tag (not shown) in thevicinity of the legged mobile robot R, and if the object is detected,determine a location of the detected object.

<Autonomous Motion Controller>

The autonomous motion controller 150 is constituted of a head controlunit 151, an arm control unit 152 and a leg control unit 153.

The head control unit 151 drives the head R4 in accordance withinstructions sent from the main controller 200, and the arm control unit152 drives the arm portions R3 in accordance with instructions sent fromthe main controller 200, and the leg control unit 153 drives the legportions R1 in accordance with instructions sent from the maincontroller 200.

<Grip Control Unit>

The gripper controller 160 drives grippers 71 in accordance withinstruction sent from the main controller 200. The grippers 71 have apair of the grippers 71R, 71L (see FIG. 2), and the pair of the grippers71R, 71L are disposed in a mirror-symmetrical manner.

Each gripper 71 is provided with an external force detector (not shown)for detecting external force affecting the gripper 71. A 6-axis forcesensor may be used as an external force detector. The 6-axis forcesensor is capable of detecting a direction of the external force, and isalso capable of detecting a force Fx in the X axis direction, a force Fyin the Y axis direction and a force Fz in the Z axis direction,respectively.

<Wireless Communication Device>

The wireless communication unit 170 is connected to the station 2 forperforming data communication with a robot manager 4 that manages thelegged mobile robot R. The wireless communication unit 170 includes apublic line communication device 171 and a wireless communication device172.

The public line communication device 171 is used as a wirelesscommunication means using public lines such as cellular phone line andPHS (Personal Handyphone System) line. Meanwhile, the wirelesscommunication device 172 is used as a short distance wirelesscommunication means using wireless LAN compliant with IEEE802.11b.

The wireless commutation unit 170, in accordance with a connectionrequest from the robot manager 4, selects either the public linecommunication device 171 or the wireless communication device 172 so asto perform data communication with the robot manager 4.

<Main Controller>

The main controller 200 serves as providing comprehensive control on thelegged mobile robot R, based on various signals and data inputted fromthe gyro sensor SR1, the GPS receiver SR2, the image processor 100, theaudio processor 110, the object detector 120, the autonomous motioncontroller 150, the gripper controller 160, the wireless communicationunit Although the embodiment of the present invention employs astructure in which the main controller 200 and the legged mobile robotcontroller 1 are implemented separately, each control unit included inthe legged mobile robot controller 1 may be incorporated in the maincontroller 200.

<Storage Device>

The storage device 300 is constituted of common storage media, andstores person data, map data, object data and speech data.

The person data is associated with data regarding a person or personsexisting within a zone where the legged mobile robot R moves (movingzone). For example, the person data may include a person identifier(ID), a name, belongings, a tag identifier, a usual location of theperson, desk locations, face images and the like.

The map data is associated with data regarding maps of the zone wherethe legged mobile robot R moves. For example, the map data may includegeographical features of the moving area, locations of walls and a deskand the like.

The object data is associated with data regarding an object or objectsto be transferred by the legged mobile robot R. For example, the objectdata may include an object identifier, a name, a sizes and weight of theobject.

The speech data is associated with data used for speech uttered by thelegged mobile robot R. For example, the speech data may include waveformdata on speech sounds in greetings in daily conversations.

Configuration of Legged Mobile Robot Controller

Hereinafter, with reference to FIG. 4 (also FIGS. 2 and 3 if necessary),descriptions will be given on the configuration of the legged mobilerobot controller 1.

FIG. 4 is a block diagram showing the legged mobile robot controller 1.As shown in FIG. 4, the legged mobile robot controller 1 serves ascontrolling an operation of loading an object gripped by the armportions R3 (gripper 71R(L)), which is one of various operationsperformed by the legged mobile robot R. The legged mobile robotcontroller 1 is constituted of a data acquisition unit 3, a whole-bodycooperative motion control unit 5 and a loading detection unit 7.

In the present invention, it is assumed that an object to be gripped bythe legged mobile robot R is a tray on which a cup or glass is placed,and a target place on which this tray is to be loaded by the leggedmobile robot R is a typical table. The legged mobile robot controller 1allows the legged mobile robot R to horizontally load the tray on thetable as far as the table has a predetermined height.

In addition, the legged mobile robot controller 1 according to theembodiment of the present invention allows the legged mobile robot R,not only to load the tray on a table having an appropriately fixedheight with standing straight and stretching the arm portions R3, butalso to load the tray even on a table that becomes lower in height thanbefore (but still within a predetermined range of height), bycooperatively controlling links of the whole body of the legged mobilerobot R.

The data acquisition unit 3 is used for acquiring posture/position dataregarding a posture and position of each link of the legged mobile robotR at the time of arriving a destination for loading the object (e.g. infront of the table), as well as external force data regarding externalforce applied on an end of the arm portion R3 (gripper end). The dataacquisition unit 3 is constituted of a posture control input subunit 3a, a current wrist posture acquisition subunit 3 b, a desired gripperend position input subunit 3 c, a position compliance input subunit 3 dand a secondary filter 3 e.

The posture control input subunit 3 a is used for inputting a positionalrelation between the shoulders and the hip (or waist) by inputting theposture/position data on the shoulders, that is, the shoulder joints 31Rto 33R of the legged mobile robot R, and the posture/position data onthe hip (or waist), that is, the joint part between the leg portions R1and the body R2.

A current wrist posture acquisition subunit 3 b is used for acquiringdata on a current wrist posture from an arm control unit 152 included inthe autonomous motion controller 150. The current wrist posture isdefined by each angle of the arm joints 35R, 35L for swirling thewrists, the wrist joints 36R, 36L about the pitch axis (Y axis) of thewrists, the wrist joints 37R, 37L about the roll axis (X axis) of thewrists.

A desired gripper end position input subunit 3 c is used for inputting adesired value for the ends of the arm portions R3 (gripper end) of thelegged mobile robot R. The desired value for each gripper end is definedby a position of the gripper 71R(L) based on a mid-point between theankle joint 16R and the ankle joint 16L.

The position compliance input subunit 3 d is used for inputting externalforce data (compliance input value) regarding external force affectingthe gripper 71R(L). The external force data increases when the gripper71R(L) touches something. Therefore, by determining whether the externalforce data increases or not, it is possible to determine whether or notan object gripped by the gripper 71R(L) of the arm portion R3 is loadedon the target place, that is, the gripper 71R(L) touches the upper faceof the table.

The secondary filter 3 e is used for filtering the external force datainputted from the position compliance input subunit 3 d into a responsefrequency of the arm portions R3 and a response frequency of the hip (orwaist) (the joint part between the leg portions R1 and the body R2).

Based on the posture/position data (position of each link or part) andthe external force data (compliance input value) acquired by the dataacquisition unit 3, the whole-body cooperative motion control unit 5controls each link (or part) to work cooperatively when the leggedmobile robot R loads the object on the target table. The whole-bodycooperative motion control unit 5 is constituted of a hip controlcorrection amount calculation subunit 5 a, a wrist posture correctionamount calculation subunit 5 b, a position deviation comparison subunit5 c, a Jacobian matrix generation subunit 5 d, desired each-axis valuecalculation subunits 5 e, 5 f, an each-axis correction amount summingsubunit 5 g, a primary delay filter 5 h, an integral calculation subunit5 i, an elbow angle control calculation subunit 5 j, an integralcalculation subunit 5 k, a forward kinematics calculation subunit 5 land a balance correction amount calculation subunit 5 m.

A cooperative motion control on each link or part by using thewhole-body cooperative motion control unit 5 is executed by outputtingto each link an instruction for a specific operation (such as a trayloading operation or a greeting operation of waving the arm portion R3.)in accordance with a whole-body plan that is information onpredetermined serial changes in posture of the legged mobile robot R.The cooperative motion control on each link is usually referred to as a“posture control” since this control is for controlling the whole-bodyposture of the legged mobile robot R.

In this posture control, the legged mobile robot controller 1 outputsinstructions to each link to keep the balance, for example, in such amanner: a polyhedron is formed by connecting movable points of each partor link as apexes of the polyhedron, and if a pair of apexes (forexample, a “first pair of apexes”) of the polyhedron sticks out, anotherpair of apexes (for example, a “second pair of apexes”) of thepolyhedron diagonally disposed to the above pair of the apexes alsosticks out, so as to compensate stick-out of the apexes of thepolyhedron each other.

With reference to FIGS. 8A to 8C, a specific explanation will be givenon how to compensate the stick-out of the polyhedron at the apexesthereof.

As show in FIG. 8A, it is assumed that a polyhedron is formed byconnecting positions of the gripper ends that are part of the right andleft arm portions R3, movable points of the links on which the right andleft arm portions R3 and the main body R2 are jointed to each other(i.e. shoulder joints), and movable points of the links on which theright and left leg portions R1 and the main body R2 are jointed to eachother (i.e. hip joints), and positions of heels or knees that are partof the right and left leg portions R1, each which becomes an apex of thepolyhedron.

Note that a first side face is formed by connecting the apexescorresponding to the right gripper end, the movable point of the linkson which the right arm portion R3 and the main body R2 are jointed toeach other, the movable point of the link on which the right leg portionR1 and the main body R2 are jointed to each other, the position of theheel or knee that is part of the right leg portion; and a second sideface is further formed by connecting the apexes corresponding to theleft gripper end, the movable point of the links on which the left armportion R3 and the main body R2 are jointed to each other, the movablepoint of the link on which the left leg portion R1 and the main body R2are jointed to each other, the position of the heel or knee that is partof the left leg portion (see the hatching part of FIG. 8A). Thepolyhedron includes the first side face and the second side facestanding opposite to the first side face.

Therefore, the first side face and the second opposite side face of thepolyhedron synchronously change each shape thereof while maintaining theidentical shape each other in accordance with changes in postures andposition of each link of the legged mobile robot R.

FIGS. 8B and 8C show side elevation views seen from the right side ofthe legged mobile robot R's proceeding direction, that is, the rightside face of the polyhedron.

If the polyhedron sticks out at a pair of the apexes thereof, thepolyhedron also sticks out at another pair of the apexes diagonallydisposed to the above pair of the apexes. For example, a posture of thelegged mobile robot R after a moving operation (i.e. after arriving atthe position in vicinity of the target place, described later) is set asa reference posture (also referred to as a “reference polyhedron”, seeFIG. 8B), as shown in FIG. 8B, and if the position of the gripper ends(i.e. first pair of the apexes, see “a” of FIG. 8) sticks out (or “isstretched”) from the reference posture when the legged mobile robot Rloads the gripped object on the target place, the position of the hipjoints (i.e. second pair of the apexes, see “b” of FIG. 8) disposeddiagonally to the position of the gripper ends also sticks out from thereference posture (see FIG. 8C).

In this way, the stick-out of polyhedron at the apexes of the polyhedronare compensated each other.

The hip control correction amount calculation subunit 5 a is used forcalculating correction amount (hip position correction amount) tocorrect the hip position (or waist position), based on theposture/position data on the shoulder joints 31R(L) to 33R(L) and theposture/position data on the hip (joint part between the leg portions R1and the body R2), both of which are inputted (to obtain a positionalrelation between the shoulders and the hip) from the posture controlinput subunit 3 a included in the data acquire unit 3, and also based ona coefficient (described later) calculated on the forward kinematicscalculation subunit 51.

The wrist posture correction amount calculation subunit 5 b is used forcalculating correction amount to correct a posture of the wrist (wristangle correction amount) so as to maintain the gripped object inparallel, based on a current wrist posture acquired on the current wristposture acquisition subunit 3 b, that is, on each angle of the arm joint35R, 35L, the wrist joints 36R, 36L and the wrist joints 37R, 37L.

The wrist posture correction amount calculation subunit 5 b calculatesthe wrist angle correction amount so that each angle of the arm joints35R, 35L, the wrist joints 36R, 36L, the wrist joints 37R, 37L does notreach a limit thereof (to avoid the limit). Specifically, the wristangle correction amount is calculated so as to change a plane shapedefined by the both wrists (the wrist joints 36R, 36L and the wristjoints 37R, 37L) by changing a height of the elbows of the arm portionsR3.

The position deviation comparison subunit 5 c is used for comparing adesired value for the gripper ends inputted from the desired gripper endposition input subunit 3 c and a current position of the gripper endsinputted from the forward kinematics calculation subunit 51. A comparedresult is obtained by subtracting the current position of the gripperends from the desired value for the gripper ends, and is outputted tothe desired each-axis value calculation subunit 5 f.

The Jacobian matrix generation subunit 5 d is used for generatingJacobian matrix J corresponding to easiness of motion of each axisincluded in each link, based on the hip position correction amountcalculated on the hip control correction amount calculation subunit 5 a,the coefficient calculated by the forward kinematics calculation subunit51 and a balance correction amount (described later) calculated by thebalance correction amount calculation subunit 5 m.

The desired each-axis value calculation subunit 5 e is used forcalculating a desired each axis value (instruction value to be sent toeach link) for the arm portions R3 (excluding the grippers 71), based onthe wrist angle correction amount calculated by the wrist posturecorrection amount calculation subunit 5 b and the Jacobian matrix Jgenerated by the Jacobian matrix generation subunit 5 d.

The desired each-axis value calculation subunit 5 f is used forcalculating a desired each axis value for the grippers 71, based on theposition deviation outputted from the position deviation comparisonsubunit 5 c and the desired each axis value for the arm portions 3Rcalculated by the desired each-axis value calculation subunit 5 e.

Note that both the desired axis value calculation subunits 5 e and 5 fcalculate a desired each axis value by using a following formula (1),where each inputted data is x (wrist angle correction amount, positiondeviation, etc.), and a desired each axis value is θ.delta θ=inv(J)*delta x  (1)

Note that “inv(J)” denotes a function using the Jacobian matrix J in theabove formula (1), and it is specifically represented as:“J*=W−1JT(kI+JW−1JT)−1”

The each-axis correction amount summing subunit 5 g sums correctionamount for each axis based on the Jacobian matrix generated on theJacobian matrix generation subunit 5 d, the desired each axis value forthe arm portions R3 calculated by the desired each-axis valuecalculation subunit 5 e, the desired each axis value for the grippers 71calculated by the desired each-axis value calculation subunit 5 f, andfurther based on the above summed result, calculates the desired eachaxis value for each axis. In other words, the each-axis correctionamount summing subunit 5 g calculates the desired each axis value basedon the desired value inputted on the desired gripper end position inputsubunit 3 c (inputting the desired position/posture), the current wristposture data acquired on the current wrist posture data acquisitionsubunit 3 b (inputting the wrist posture), and the positional relationbetween the shoulders and the hip inputted on the posture control inputsubunit 3 a (inputting stick-out compensation).

The primary delay filter 5 h is used for smoothing output of the desiredeach axis value for each axis calculated by the axis correction amountsumming subunit 5 g, and multiplying the desired each axis value by thetransfer function (1/Ts+1 (T: time constant, s: differential operator)).The reason for delaying the output of the desired each axis value is toadjust characteristics of the legged mobile robot R's actual body motionto a model characteristics that is predetermined for the legged mobilerobot R's body motion.

The integral calculation subunit 5 i is used for providing an integralcalculation for the desired each axis value which has been multiplied bythe transfer function by the primary delay filter 5 h. The resultobtained by the integral calculation subunit 5 i is outputted to thebalance correction amount calculation subunit 5 m, and via the maincontroller 200 to the leg control unit 153 of the autonomous motioncontroller 150 as well, thereby applying the result on the legged mobilerobot R's motions.

Based on the desired each axis value for each axis which is calculatedby the axis correction amount summing subunit 5 g, the elbow anglecontrol calculation subunit 5 j calculates a desired elbow angle value,based on which the shoulder angle correction amount is calculated. Thedesired elbow angle value is used for setting angles of the elbow joints34R, 34L about the pitch axis (Y axis) of each elbow. The shouldercorrection amount is a correction amount for correcting angles of theshoulder joints 31R, 31L about the pitch axis (Y axis) of the shoulders(joint part between the arm portions R3 and the body R2), the shoulderjoints 32R, 32L about the roll axis (X axis) of the shoulders and theshoulder joints 33R, 33L for swirling each arm portion (about the Zaxis).

The integral calculation subunit 5 k is used for providing an integralcalculation on the shoulder angle correction amount that is calculatedby the elbow angle control calculation subunit 5 j. The resultcalculated by the elbow angle control calculation subunit 5 j isoutputted to the balance correction amount calculation subunit 5 m, andvia the main controller 200 to the arm control unit 152 of theautonomous motion controller 150, as well, thereby applying the resulton the legged mobile robot R's motions.

In the integral calculation subunits 5 i and 5 k, a current state(before motion) is represented as “state (n−1)”, state change amount ina micro time period is represented as “delta (n−1)”, and a state afterthe motion is represented as “state (n)”, where the state after themotion “state (n)” is calculated by using the following formula (2)state (n)=state (n−1)+delta (n−1)  (2)

Based on the result calculated by the integral calculation subunit 5 kand the balance correction amount calculated by the balance correctionamount calculation subunit 5 m, the forward kinematics calculationsubunit 51 is used for calculating a coefficient to transform a lineconnecting the joints (of each link) at a joint angle into a coordinate.In other words, by using this coefficient, two links of the leggedmobile robot R can be transformed into an appropriate line.

The balance correction amount calculation subunit 5 m is used forcalculating the balance correction amount based on the result obtainedon the integral calculation subunit 5 i. The balance correction amountcompensates the center-of-gravity shift amount of the body R2 and theleg portions R1, that is, a moment due to the body motion that is causedwhen the legged mobile robot R stretches the arm portions R3.

The loading detection unit 7 is used for determining whether or not anobject is loaded on the target place based on the external force dataregarding external force affecting the gripper 71R(L), which is inputtedby the position compliance input subunit 3 d (compliance input value).The loading detection unit 7 includes a detection subunit 7 a.

The determination subunit 7 a is used for determining whether or not theexternal force data exceeds a predetermined value. The legged mobilerobot controller 1 controls the object loading operation by keeping thearm portions R3 of the legged mobile robot R stretching; or by keepingthe leg portions R1 thereof bent at the knee joints 14R (L) until it isdetermined that the external force data exceeds a predetermined value,and if it is determined that the external force data exceeds thepredetermined value, it is determined the object loading operation hasbeen completed. Then, the legged mobile robot controller 1 controls thelegged mobile robot R to return to the original posture. (“returnoperation”, described later).

According to the legged mobile robot controller 1 having such astructure as described above, it is possible to load a gripped object inparallel on a target place having a height where a stretchable range ofthe arm portions R3 is enhanced with no operator's handling, whilemaintaining the posture of the legged mobile robot R in a predeterminedposture based on the posture/position data acquired by the data acquireunit 3.

Overall Operation from Receiving an Object to Loading the Object

With reference to a flow chart of FIG. 5, descriptions will be given onan overall operation from receiving an object to loading the object,which is performed by the legged mobile robot R (see FIGS. 2, 3, 4 ifnecessary).

<Moving Operation to Receiving Position>

An explanation will be given on a moving operation of moving to areceiving position where the legged mobile robot R receives the object(S1).

First, the legged mobile robot R is in a standby state at apredetermined home-position. When the legged mobile robot R receivesexecution-instruction signals from the robot manager 4, the leggedmobile robot R starts moving from the home-position to a usual locationof a person (see “person data” in <Storage Device>). When arriving atthe usual location of the person, the legged mobile robot R stops themoving operation, and starts looking for the person. If a tag identifierof the person is detected by the object detector 120, the legged mobilerobot R acquires an image of the person by using cameras C, C, and movestoward the person.

If the legged mobile robot R does not detect the tag identifier of theperson within a predetermined time period, the legged mobile robot Rgenerates operation report signals reporting that it is impossible toperform the current task, outputs the signals to the robot manager 4,and then returns to the home-position.

<Receiving Operation>

A description will be provided on a receiving operation to receive theobject (tray) performed by the legged mobile robot R (S2).

When arriving at the receiving position, the legged mobile robot R holdsout the gripers 71R, 71L with the thumb and the fingers open at apredetermined receiving height. At this time, the legged mobile robot Rholds out the grippers 71R, 71L in such a manner that a distance fromeach gripper 71 to the person becomes constant, and the grippers 71R,71L are held out toward a center (central vertical line) of the personwhich is calculated by the mobile object extraction unit 102.

After completion of holding-out of the grippers 71R, 71L, a receivingstatus of the legged mobile robot R becomes a “standby for receiving”mode, and utters “Please, give me the object (tray)”. During staying inthe “standby for receiving” mode, if the legged mobile robot R detectsthat an external force Fx is greater than Fx1 on the 6 axis forcesensors 62R, 62L, the receiving status is set in a “receiving” mode, sothat the legged mobile robot R starts to close (the thumbs and thefingers of) the grippers 71R, 71L. During staying in the “receiving”mode, if the legged mobile robot R detects on the 6 axis force sensors62R, 62L that an external force Fx becomes Fx2 or less, or the gripangle deviation θ becomes a predetermined value of θ1 or less, thereceiving status is set in a “completion of receiving” mode.

If an open angle of the gripper 71R (71L), that is, the grip angledeviation θ equals to a predetermined value of θ3 or more, it isdetermined that the object is thick and the grippers 71R, 71L have bothgripped the object, and the receiving status is set in a “completion ofgripping” mode.

If at least one of the grippers 71R, 71L has a grip angle deviation θless than θ3, the receiving status is set in a “determining of gripping”mode, and determines whether or not the legged mobile robot R isgripping the object.

Specifically, in the “determining of gripping” mode, the legged mobilerobot R, while opening and closing the thumb and the fingers of eachgripper 71, detects a reaction force Fy from the object on the 6 axisforce sensors 62R, 62L. If the reaction force Fy equals to apredetermined value of Fy1 or more, it is determined that the grippingis succeeded, and the receiving status is set in a “completion ofreceiving”, and at the same time, the grippers 71R, 71L grip the object.If the reaction force Fy is less than Fy1, it is determined that thegripping fails, and the receiving status is set in a “fail in gripping”.

<Retry Operation>

Now, an explanation will be give on a retry operation.

If the receiving status of the grippers 71R, 71L is set in the “fail inreceiving”, and at least one of the 6 axis force sensors 62R, 62Ldetects that the external force Fy equals to a predetermined value ofFy2 or more, the receiving status is set in a “standby for hand-over”,and the legged mobile robot R utters, “Please, take up the tray and giveit to me again”.

If the legged mobile robot R detects that the external force Fx equalsto a predetermined value of Fx5 or more at least one of the 6 axis forcesensors 62R, 62L on which the object (tray) is gripped, the receivingstatus is set in a “handing over”, and the gripper 71R (71L) opens thethumb and the fingers, and then the legged mobile robot R retries thereceiving operation.

If the grip angle deviation θ equals to a predetermined value of θ(forexample, θ=0) or less, the legged mobile robot R utters, “Please give methe object (tray) again”, and the grippers 71R, 71L open the thumb andthe fingers thereof, and then the receiving operation is retried.

<Transfer Operation>

A description will be given on an object transfer operation (S3).

After the operation of gripping the object is completed, the leggedmobile robot R moves the grippers 71R, 71L toward a location out of theimage zone where the cameras C, C can take images (blind spot). Thisoperation is to prevent the gripped object (tray) from blocking sight ofthe cameras C, C. The legged mobile robot R starts to move from thereceiving position to a position in vicinity of the target place(loading place) When arriving at the position in vicinity of the targetplace, the legged mobile robot R stops moving and starts to look for thetarget place.

<Loading Operation>

The legged mobile robot R, which has reached the position in vicinity ofthe target place, performs the loading operation to load the object onthe target place (S4). The legged mobile robot R, after completion ofthe loading operation, returns to a status of gripping no object, andthen moves back to the home-position.

A detailed explanation will be given on the loading operation withreference to FIG. 6.

Detailed Operation in Loading Operation by Legged Mobile Robot R

FIG. 6 shows a flow chart for explaining the legged mobile robot R'soperation of loading the object on the target place (on the table)controlled by the legged mobile robot controller 1 (see FIGS. 2, 3, 4 ifnecessary).

The legged mobile robot controller 1, after the transfer operation(after arriving at the position in vicinity of the target place),acquires posture/position data showing the legged mobile robot R'sstatus from the data acquire unit 3 (S11).

Specifically, the legged mobile robot controller 1 inputsposture/position data on the shoulder joints 31R to 33R, andposture/position data on the joint part between the leg portions R1 andthe body R2 by the posture control input subunit 3 a included in thedata acquire unit 3. The legged mobile robot controller 1 also acquires,by the current wrist posture acquisition subunit 3 b, each angle of thearm joints 35R, 35L for swirling each wrist, of the wrist joints 36R,36L about the pitch axis (Y axis) of each wrist and of the wrist joints37R, 37L about the roll axis (X axis) of each wrist; and inputs eachposition of the ankle joints 16R, 16L. Then, the legged mobile robotcontroller 1 inputs positions of the ankle joints 16R, 16L and positionsof the grippers 71R, 71L (gripper end positions) by the desired gripperend position input unit 3 c.

Following the above steps, by the whole-body cooperative motion controlunit 5, the legged mobile robot controller 1 determines how to input theposture control, based on the posture/position data on each linkposition acquired by the data acquire unit 3, in order to controlmotions of the arm portions R3 and the leg portions R1 such that theacquired posture/position data on each link position agrees with awhole-body plan providing information on a predetermined series ofposture changes of the legged mobile robot R (hip gain “ON”) (S12).Specifically, the legged mobile robot controller 1 determines the orderof processing the posture/position data so as to cooperatively controlthe whole-body posture of the legged mobile robot R; and by providingthe cooperatively control on the whole-body posture, an operation zonefor loading the object on the target place is secured.

In other words, the legged mobile robot controller 1 secures theoperation zone by providing a control of the whole-body cooperativemotion control unit 5 so as to compensate the stick-out at the apexes ofthe polyhedron, which is formed by connecting the apexes thereofcorresponding to each position of the gripper ends (positions of thegrippers 71R, 71L), the shoulders (positions of the shoulder joints31R(L) to 33R(L)), the hip (positions of the joint part between the legportions R1 and the body R2) and the heals (positions of the anklejoints 16R(L)).

The legged mobile robot controller 1 starts to load the object on thetarget place in a condition that the posture control is set to “ON”,that is, in a condition of securing the operation zone (S13).

At this time, by use of the whole-body cooperative motion control unit5, the legged mobile robot controller 1 controls each angle of the armjoints 35R, 35L for swirling the wrists, the wrist joints 36R, 36L aboutthe pitch axis (Y axis) of each wrist, and the wrist joints 37R, 37Labout the roll axis (X axis) of each wrist not to exceed a thresholdvalue (to avoid a limit), so as to maintain the object in parallel to ahorizontal plane.

The legged mobile robot controller 1 inputs the external force dataregarding the external force affecting the gripper or grippers 71 by theposition compliance input subunit 3 d, and determines on detectionsubunit 7 a included in the loading detection unit 7 whether or not theexternal force becomes the predetermined value or more, wherebydetermining whether or not the object is loaded (S14). Specifically, theloading detection unit 7 determines that the object is loaded on thetarget place if the external force data becomes the predetermined valueor more, that is, if the external force affecting the gripper orgrippers 71 becomes the predetermined value or more, it implies that thegripper or grippers 71 securely touches the target place. When loadingthe object on the target place, the legged mobile robot R may utters, “Imade some tea for you”, through the audio synthesis unit 111 of theaudio processor 110 and the speaker S.

On the detection subunit 7 a included in the loading detection unit 7,the legged mobile robot controller 1 does not determine that the loadingis completed until the external force data becomes the predeterminedvalue or more (“No” at S14). In this case, the legged mobile robotcontroller 1 returns to S13 to continue the loading operation. Thelegged mobile robot controller 1 determines that the loading iscompleted if the external data becomes the predetermined value or more(“Yes” at S14). After completing the loading operation, the leggedmobile robot controller 1 sets the current height of the arm portions R3to a default value for the return operation (i.e. operation of puttingthe arm portions R3 down to the side of the body R2 respectively, orreturn to a state of having no object) (S15), and resets the hip gain“ON” and starts the return operation (S16). In the return operation, thelegged mobile robot R operates in such a manner that the robot R putsdown the arm portions R3, and stretches the bend of the leg portions R1at the joint part between the leg portions R1 and the body R2 so thatthe position of the joint part meets a line along the vertical directionof the center of gravity, whereby returning to the original posture.

Operation Conditions and Operation Region of Legged Mobile Robot R

With reference to FIG. 7 and FIGS. 9 to 11, explanations will be givenon the operation conditions of the legged mobile robot R in comparisonwith a conventional control (i.e. without control by the legged mobilerobot controller 1), as well as on the operation zone of Legged MobileRobot R in a specific example.

In FIG. 7, the legged mobile robot R and a series of operations thereofare depicted with straight lines for simplification. FIG. 7A shows thetransfer operation of the legged mobile robot R, FIG. 7B shows theloading operation, and FIG. 7C shows the return operation, and asequential direction of each operation is represented by an arrow,respectively.

As shown in FIGS. 7, the legged mobile robot R moves towards a targetplace S with gripping an object M, and then loads the object M on thetarget place S (particularly see a right-most figure in FIG. 7B). Thelegged mobile robot controller 1 detects the completion of the loadingoperation based on the reaction force from the target place S and thearm portions R3 (grippers 71, see FIG. 2) when the legged mobile robot Rloads the object M on the target place S, that is, by using thecompliance control.

FIGS. 9 and 10 show differences between a case in which there isprovided a control by use of the legged mobile robot controller 1(controlled) and a case in which there is provided no control thereby(uncontrolled), when legged mobile robot R performs the loadingoperation.

FIG. 9A shows the controlled case and FIG. 9B shows the uncontrolledcase.

As shown in FIG. 9B, in the uncontrolled case, if performing the loadingoperation, the legged mobile robot R not only secures no operation zonebut also inclines backward as shown in a bold broken line of FIG. 9B.Meanwhile, in the controlled case as shown in FIG. 9A, the legged mobilerobot. R compensates the stick-out at the apexes of the polyhedronformed by connecting 8 points of the body (both shoulders), the gripperends, the hip (joint part between the body and the leg portions) andankles, so as to secure the operation zone depicted with hatching, whilemaintaining an excellent balance of the whole body. The polyhedron maybe formed by using the knee positions in stead of the ankle positions asthe apexes thereof, as shown in FIG. 9A.

FIGS. 10A and 10C show the uncontrolled case, and FIGS. 10B and 10D showthe controlled case.

As for a motion “following the arm compliance control” with reference toFIG. 10, in the uncontrolled case (FIG. 10A), the hip (joint partbetween the body and the leg portions) does not move (follow) inaccordance with a force applied on the gripper ends. On the other hand,in the controlled case (FIG. 10B), the hip (joint part between the bodyand the leg portions) moves (follows) in accordance with a force appliedon the gripper ends.

As for a motion “compensating the wrist movable angle”, in theuncontrolled case (FIG. 10C), the gripper ends do not follow the desiredposture, meanwhile in the controlled case (FIG. 10D), the gripper endsfollow and maintain the desired posture.

FIGS. 11 and 12 specifically show the difference between the case inwhich there is provided the control by use of the legged mobile robotcontroller 1 (controlled) and the case in which there is provided nocontrol thereby (uncontrolled), when the legged mobile robot R performsthe loading operation.

FIG. 11A shows the uncontrolled case, and FIG. 11B shows the controlledcase.

With reference to FIG. 11B, it can be seen that the legged mobile robotR can put the hip (waist) down to a height of 420 mm from the groundplane, and secure the operation zone having a width of 100 mm and aheight of 120 mm (680 m to 800 m from the ground surface) as depictedwith hatching in FIG. 11B.

FIG. 12 shows secured zones for the operation zone of FIG. 11 seen fromthe top of the legged mobile robot R. “With Arm Only” represents asecured zone for the operation zone in the uncontrolled case, and “WithWhole-body” represents a secured zone for the operation zone in thecontrolled case. The controlled case (“With Whole-body”) can secure anoperation zone as large as twice or more of the uncontrolled case (“WithArm Only”) on a planar basis, as shown in FIG. 12.

In other words, the controlled case “With Whole Body” secures theoperation zone by bending the hip joints 12R(L) and the knee joints14R(L) of the legged mobile robot R's leg portions R1.

As describe above, there have been explanations provided on theembodiment of the present invention. However, the embodiment is notlimited thereto. For example, although there have been providedexplanations chiefly on the legged mobile robot controller 1 in theembodiment of the present invention, the explanations may be applied ona method or methods into which the legged mobile robot controller 1 isincorporated.

The legged mobile robot R can be changed or modified in the designthereof such as the numbers of joints and positions.

According to the embodiment of the present invention, it is possible toprovide a legged mobile robot that loads a gripped object on a targetplace having a height where a stretchable range of arm portions thereofis enhanced, with no operator's handling, while maintaining a posture ofthe legged mobile robot in accordance with a predetermined posture modelbased on the posture/position data. It is also possible for the leggedmobile robot to load the gripped object in parallel with no operator'shandling, as far as the target place has a height within a predeterminedrange.

The embodiment according to the present invention has been explained asaforementioned. However, the embodiment of the present invention is notlimited to those explanations, and those skilled in the art ascertainthe essential characteristics of the present invention and can make thevarious modifications and variations to the present invention to adaptit to various usages and conditions without departing from the spiritand scope of the claims.

1. A legged mobile robot controller for controlling a legged mobilerobot comprising arm portions for gripping an object, each arm potionshaving links; leg portions for moving, each leg portion having links; amain body of the legged mobile robot joined to the arm portions and theleg portions, based on posture/position data regarding a posture and aposition of each link of the legged mobile robot and on an externalforce data regarding an external force affecting the arm portion orportions thereof, the legged mobile robot controller comprising: a dataacquire unit for acquiring the posture/position data and the externalforce data; a whole-body cooperative motion control unit for controllingmotions of the leg portions in accordance with motions of the armportions, based on the posture/position data acquired by the dataacquire unit, when the legged mobile robot loads the gripped object withthe arm portions on a target place; and a loading detection unit fordetecting that the gripped object with the arm portions has been loadedon the target place by the motions controlled by the whole-bodycooperative motion control unit, based on the external force dataacquired by the data acquire unit, wherein the whole-body cooperativemotion control unit controls in such a manner that, if the loadingdetection unit detects that the gripped object is not loaded on thetarget place when a position of the arm is put down or stretched, eachlink of the leg portions is bent at part where each link is jointed toeach other.
 2. The legged mobile robot controller according to claim 1,wherein the whole-body cooperative motion control unit controls in sucha manner that each link of the leg portions is bent at part where eachlink is jointed to each other while the gripped object gripped with thearm portions is maintained in parallel.
 3. A legged mobile robotcomprising the legged mobile robot controller according to claim
 2. 4. Alegged mobile robot comprising the legged mobile robot controlleraccording to claim
 1. 5. A legged mobile robot controller forcontrolling a legged mobile robot comprising arm portions for grippingan object, each arm potions having links; leg portions for moving, eachleg portion having links; a main body of the legged mobile robot joinedto the arm portions and the leg portions, based on posture/position dataregarding a posture and a position of each link of the legged mobilerobot and on an external force data regarding an external forceaffecting the arm portion or portions thereof, the legged mobile robotcontroller comprising: a data acquire unit for acquiring theposture/position data and the external force data; a whole-bodycooperative motion control unit for controlling motions of the legportions and the arm portions when the legged mobile robot loads theobject gripped with the arm portions on a target place based on theposture/position data acquired by the data acquire unit, the motions ofthe leg portions and the arm portions being controlled in such a mannerthat: a polyhedron is assumed, which is formed by connecting all thepoints of each part or link of the arm portions and the leg portions,each which becomes an apex of the polyhedron, where a motion at someapexes of the polyhedron is compensated by a motion at other apexesthereof, and a loading detection unit for detecting that the grippedobject with the arm portions has been loaded on the target place by themotions controlled by the whole-body cooperative motion control unit,based on the external force data acquired by the data acquire unit,wherein the apexes of the polyhedron at least comprises: positions ofgripper ends that are part of the arm portion; movable positions of thelinks at which the arm portions and the main body are joined to eachother; movable positions of the links at which the leg portions and themain body are joined to each other; and positions of heels or knees thatare part of the leg portions.
 6. The legged mobile robot controlleraccording to claim 5, wherein the polyhedron comprises a first pair ofthe apexes and a second pair of the apexes, which are disposeddiagonally to each other, the first pair of the apexes of the polyhedroncomprises apexes of the right and left side faces that stand opposite toeach other, the second pair of the apexes of the polyhedron comprisesapexes of the right and left side faces that stand opposite to eachother, and the whole-body cooperative motion control unit controls themotions of the arm portions and the leg portions in such a manner that:if the polyhedron sticks out at either of the first pair or the secondpair of the apexes of the polyhedron which are disposed diagonally toeach other from a predetermined reference polyhedron at a correspondingpair of apexes thereof, the other pair of the apexes of the polyhedronalso sticks out from the predetermined reference polyhedron at acorresponding pair of apexes thereof, so as to compensate the motion atsome apexes of the polyhedron by the motion at other apexes thereof. 7.The legged mobile robot controller according to claim 6, wherein thelegged mobile robot comprises the arm portions and the leg portions onright and left sides respectively, the polyhedron comprise a first sideface and a second side face that are standing opposite to each other,and the first side face is formed by connecting apexes comprising: aposition of a gripper end that is part of the right arm portion; amovable position of the link at which the right arm portion and the mainbody are joined to each other; a movable position of the link at whichthe right leg portion and the main body are joined to each other; and aposition of a heel or a knee that is part of the right leg portion, eachwhich becomes an apex of the first side face and the second side face isformed by connecting apexes comprising: a position of a gripper end thatis part of the left arm portion; a movable position of the link at whichthe left arm portion and the main body are joined to each other; amovable position of the link at which the left leg portion and the mainbody are joined to each other; and a position of a heel or a knee thatis part of the left leg portion, each which becomes an apex of thesecond side face, wherein the whole-body cooperative motion control unitcontrols in such a manner that the first and the second side facessynchronously change each shape thereof while maintaining the identicalshape each other in accordance with changes in posture or position ofeach part or link of the legged mobile robot.
 8. A legged mobile robotcomprising the legged mobile robot controller according to claim
 7. 9. Alegged mobile robot comprising the legged mobile robot controlleraccording to claim
 6. 10. The legged mobile robot controller accordingto claim 5, wherein the whole-body cooperative motion control unitcontrols in such a manner that each link of the leg portions is bent atpart where each link is jointed to each other while the gripped objectgripped with the arm portions is maintained in parallel.
 11. A leggedmobile robot comprising the legged mobile robot controller according toclaim
 5. 12. A legged mobile robot control method for controlling alegged mobile robot comprising arm portions for gripping an object, eacharm potions having links; leg portions for moving, each leg portionhaving links; a main body of the legged mobile robot joined to the armportions and the leg portions, based on posture/position data regardinga posture and a position of each link of the legged mobile robot and onan external force data regarding an external force affecting the armportion or portions thereof, the legged mobile robot control methodcomprising steps of: by a data acquire unit, acquiring theposture/position data and the external force data; by a whole-bodycooperative motion control unit, controlling motions of the leg portionsin accordance with motions of the arm portions, based on theposture/position data acquired by the data acquire unit, when the leggedmobile robot loads the gripped object with the arm portions on a targetplace; and by a loading detection unit, detecting that the grippedobject with the arm portions has been loaded on the target place by themotions controlled by the whole-body cooperative motion control unit,based on the external force data acquired by the data acquire unit,wherein the whole-body cooperative motion control unit controls in sucha manner that, if the loading detection unit detects that the grippedobject is not loaded on the target place when a position of the arm isput down or stretched, each link of the leg portions is bent at partwhere each link is jointed to each other.
 13. The legged mobile robotcontrol method according to claim 12, wherein, in the controlling stepby the whole-body cooperative motion control unit, the whole-bodycooperative motion control unit controls in such a manner that each linkof the leg portions is bent at part where each link is jointed to eachother while the gripped object gripped with the arm portions ismaintained in parallel.
 14. A legged mobile robot control method forcontrolling a legged mobile robot comprising arm portions for grippingan object, each arm potions having links; leg portions for moving, eachleg portion having links; a main body of the legged mobile robot joinedto the arm portions and the leg portions, based on posture/position dataregarding a posture and a position of each link of the legged mobilerobot and on an external force data regarding an external forceaffecting the arm portion or portions thereof, the legged mobile robotcontrol method comprising steps of: by a data acquire unit, acquiringthe posture/position data and the external force data; by a whole-bodycooperative motion control unit, controlling motions of the leg portionsand the arm portions when the legged mobile robot loads the objectgripped with the arm portions on a target place based on theposture/position data acquired by the data acquire unit, the motions ofthe leg portions and the arm portions being controlled in such a mannerthat: a polyhedron is assumed, which is formed by connecting all thepoints of each part or link of the arm portions and the leg portions,each which becomes an apex of the polyhedron, where a motion at someapexes of the polyhedron is compensated by a motion at other apexesthereof, and by a loading detection unit, detecting that the grippedobject with the arm portions has been loaded on the target place by themotions controlled by the whole-body cooperative motion control unit,based on the external force data acquired by the data acquire unit,wherein the apexes of the polyhedron at least comprise: positions ofgripper ends that are part of the arm portions; movable positions of thelinks at which the arm portions and the main body are joined to eachother; movable positions of the links at which the leg portions and themain body are joined to each other; and positions of heels or knees thatare part of the leg portions.
 15. The legged mobile robot control methodaccording to claim 14, wherein, in the controlling step by thewhole-body cooperative motion control unit, the whole-body cooperativemotion control unit controls the motions of the arm portions and the legportions in such a manner that: the polyhedron comprises a first pair ofthe apexes and a second pair of the apexes, which are disposeddiagonally to each other, the first pair of the apexes of the polyhedroncomprises apexes of the right and left side faces that stand opposite toeach other, the second pair of the apexes of the polyhedron comprisesapexes of the right and left side faces that stand opposite to eachother, and if the polyhedron sticks out at either of the first pair orthe second pair of the apexes of the polyhedron which are disposeddiagonally to each other from a predetermined reference polyhedron at acorresponding pair of apexes thereof, the other pair of the apexes ofthe polyhedron also sticks out from the predetermined referencepolyhedron at a corresponding pair of apexes thereof, so as tocompensate the motion at some apexes of the polyhedron by the motion atother apexes thereof.
 16. The legged mobile robot control methodaccording to claim 15, wherein the legged mobile robot comprises the armportions and the leg portions on right and left sides respectively, inthe controlling step by the whole-body cooperative motion control unit,the whole-body cooperative motion control unit controls the motions ofthe arm portions and the leg portions in such a manner that: thepolyhedron comprises a first side face and a second side face that standopposite to each other, the first side face is formed by connecting: aposition of a gripper end that is part of the right arm portion; amovable position of the link at which the right arm portion and the mainbody are joined to each other; a movable position of the link at whichthe right leg portion and the main body are joined to each other; and aposition of a heel or a knee that is part of the right leg portion, eachwhich becomes an apex of the first side face, and the second side faceis formed by connecting: a position of a gripper end that is part of theleft arm portion; a movable position of the link at which the left armportion and the main body are joined to each other; a movable positionof the link at which the left leg portion and the main body are joinedto each other; and a position of a heel or a knee that is part of theleft leg portion, each which becomes an apex of the second side face,wherein the first and the second side faces synchronously change eachshape thereof while maintaining the identical shape each other inaccordance with changes in posture or position of each part or link ofthe legged mobile robot.
 17. The legged mobile robot control methodaccording to claim 14, wherein, in the controlling step by thewhole-body cooperative motion control unit, the whole-body cooperativemotion control unit controls in such a manner that each link of the legportions is bent at part where each link is jointed to each other whilethe gripped object gripped with the arm portions is maintained inparallel.